A Promise to Keep
by SilverChaser17
Summary: Zeref is back but what does he want with Lucy? Natsu promises Lucy that he'll protect her from danger but will that prove to be too hard of a promise to keep? Sorry for the bad summary but I hope you enjoy my first fan fiction :)
1. Chapter 1

"Lucy!" Lucy looked out her bedroom window to find Natsu, her partner, standing out on the street looking up at her with that signature smile of his that she loves so much.  
"Natsu, why won't you just come up here?"  
"The last time I did, you kicked me out of your window and told me to stay out."  
Lucy sighed. _He really isn't that bright is he, _she thought to herself.  
"That's because I just came out from a bath and you were in my room. Just come up here already."  
Natsu and Lucy are really close but Natsu tends to forget that Lucy needs her own privacy too. But when it comes to a job request, they work really well together. Lucy had just finished getting dressed when Natsu kicked down the front door to her apartment screaming,  
"Where's the food?!"  
"Hey! You have to pay for that yourself."  
Lucy stood in her living room, hands on her hips, as she watched Natsu sniff around her room, trying to find where Lucy hid her groceries this time. She has to find a new spot at least twice a week.  
_Why does he always have to eat while he's here?  
_Natsu suddenly stopped dead in his tracks as he smelt another scent. It was an old but familiar scent that Natsu recognized from a long time ago. It brought back memories of death and chaos.  
"Someone's been here, recently."  
"Huh? Who is it; do I know them?"  
Natsu looked at her with frantic eyes.  
"Zeref was in this room, recently."

* * * *

"That's impossible. No one's seen Zeref since Tenroujima, seven years ago."  
Lucy had a hard time believing this sudden news that _he _had been in her house.  
"There's no mistake; Zeref was here."  
She felt a little faint as she understood what that meant. Zeref had stood right where they were standing, watching Lucy. The question is, why?  
"Natsu, what does this mean?"  
He just shook his head.  
"I don't know but he's interested in you for some reason. You're not safe here anymore."  
"So then what now? Should we tell the guild?"  
What's going on with Lucy? Normally she's the one answering Natsu's questions but this whole Zeref thing has really freaked her out.  
_If Zeref's back, does that mean that Achnolognia's back as well?  
_All of this was too much for her to take. It brought back unwanted memories of the terror and fear she felt while facing Achnolognia and Grimoire Heart.  
Suddenly, Lucy collapsed to the ground and was out cold once her head hit the floor.  
"Lucy!"  
Natsu rushed to her side and held her in his arms as she slowly regained consciousness.  
"Dammit. Lucy are you alright?"  
"Yeah. Sorry for that. I'm fine, really."  
Lucy tried to sit herself up but found that her arms couldn't hold her up and she fell into Natsu's arms.  
"That's it Lucy. We're going to see Gramps."  
He stood and picked up Lucy in his arms. Lucy started to blush a little.  
"S...stop it Natsu. I can walk on my own."  
She started to protest but stopped once she looked up at his face. Natsu looked ready to hurt someone.  
"No one messes with Fairy Tail and gets away with it. Don't worry Lucy; I swear that I'll protect you."  
As Natsu ran across Magnolia to the guild hall, Lucy never said a word, she just closed her eyes and rested her head on his chest, listening to the beating of his heart.  
"Thank you Natsu." 


	2. Chapter 2

As they approached the guild hall, Gray came running towards them, shortly followed by Juvia.  
"Lucy! Are you okay?!"  
"Ah, Gray-sama! Why don't you ever worry about Juvia?"  
Juvia was obviously jealous but when she looked at Lucy she also became worried.  
"Natsu-san, what happened to Lucy-san?"  
Natsu grit his teeth  
"Zeref's back."  
That's all he had to say. Natsu and the others ran into the guild, where they lay Lucy on a table. Levy and Wendy came rushing in followed by Happy and Carla.  
"Lu-chan, can you hear me?"  
Levy was almost in tears as she saw her best friend lying there, motionless. Wendy was already using her magic to heal Lucy and bring her mind out of the darkness.  
"Don't worry; Lucy-san just has a mild concussion. She should wake up soon."  
Natsu looked at Wendy.  
"Thanks Wendy."  
And so, the guild sat down as Natsu explained what had happened at Lucy's apartment. It turns out that Makarov was at Blue Pegasus having a meeting with Master Bob about something secret. They had to help themselves for now until he got back. Levy sat Lucy's side, holding her hand as she tried to choke back her tears. She then turned to look at Natsu.  
"You need to stay with Lu-chan for a while. I don't think it's safe for her to be alone while Zeref's back."  
Everyone murmured in agreement except for Natsu who looked a little shocked.  
"What! Why do I have to? Can't Erza?"  
Gray shook his head.  
"Erza's gone on an S Class job and won't be back for a while."  
"Besides," Levy smiled, "You practically live at her house anyways, how is this any different?"  
Natsu's face grew a little red but he didn't argue with her. Suddenly, Lucy murmured in her sleep.  
"N...su…"  
They all gasped and listened closer as she spoke again.  
"Natsu, don't leave me."  
Everyone looked at Natsu and saw him blushing. It was official; Natsu was staying with Lucy.


	3. Chapter 3

When Lucy woke up, Natsu was gone and she was at the guild with Levy and Wendy sleeping at her side. Carla was sitting next to Happy and they seemed to be having an intense discussion.  
"We need to keep her away from Zeref at all costs or else _it _will actually happen."  
Happy just sat there looking at her with concern in his eyes. He didn't know how to comfort Carla who was obviously upset about something; all he could do was stand and watch.  
_Was it another vision, _Lucy thought to herself.  
Carla looked over and saw that Lucy was finally conscious.  
"Oh good; we were beginning to wonder when you would finally wake up."  
"What happened?"  
"Natsu brought you back here but you were already unconscious after hitting your head. Thanks to Wendy, you're able to wake up a little sooner than normal."  
Lucy used her own strength that had returned to her to sit herself up. She looked around but didn't see Natsu anywhere. In fact, no one else was in the guild hall except for the five of them.  
"Where is everyone?"  
Happy went over to Lucy's side.  
"The entire guild has been set up into teams around Magnolia to find Zeref. Natsu's at your place moving in the last of his things. He's going to be living with you for a while to keep you safe."  
"Huh?!"  
Lucy understood why he was moving in but she didn't know if she could handle him for long. Besides, if he somehow found out that she actually… No, now's not the time to be thinking of that.  
"Carla did you have another vision?"  
Carla looked up in surprise but solemnly nodded.  
"It was very strange and I don't understand most of it myself. I saw a golden key in the sky among the stars. Zeref was also in it. He kept saying something about an 'Eternal Key'. Then all I saw was darkness and I heard a blood curdling female scream above the sound of thunder."  
Lucy felt a shiver go down her spine just imagining it. Poor Carla had to watch the entire thing by herself.  
_Were all visions like this?_


	4. Chapter 4

Lucy was finally allowed to go home but Wendy told her to go with someone so Happy went with her.  
"So if anyone attacks you, I can fly us to safety. That is if my arms can handle a lot weight for that long."  
And so, the two set out back to Lucy's apartment; Lucy had gained some new knowledge and Happy had received a few well earned bruises. They were hoping to meet Natsu there and have something to eat.

The night gave Magnolia an entire new personality. The streets that are normally full of people and laughter now belong to the shadows. You could hear the sound of your own footsteps echo down dark alleys, making it sound like you're being followed. However, it wasn't her own footsteps that Lucy heard as she and Happy walked across town to Lucy's apartment.  
"Happy, do you think that someone's following us?"  
"Aye. Lucy, I'm scared."  
Happy was shaking with fear as he also listened to the footsteps that only seemed to grow closer.  
"It's okay; I have a plan."  
Lucy was making that up of course but seeing her friend so scared brought out her own courage.  
_Someone has to brave _she thought.  
"Happy, I need you to find Natsu. Tell him to meet at Magnolia Station. I'll hold this guy of until then."  
Even though she knew she had no chance of surviving against Zeref, but if she could at least save Happy, then she would be able to die knowing she saved someone in the end.  
"But Lucy..."  
"Don't argue! Go!"  
And so, feeling ashamed at abandoning his friend, Happy left with a quick burst of wings and raced to Natsu. He's the only one who might be able to help Lucy; stopping Zeref was impossible, even for Natsu.  
It was up to him to save Lucy.

Now that Happy was out of the picture, Lucy could finally begin the race for her life. She took the risk and looked behind her to find none other than the dark mage Zeref himself. But his eyes were closed.  
_Is he sleep walking?  
_Great, even in his dreams he's chasing her! Trying to be as silent as possible, she reached towards her keys. Virgo would be able to help her escape if she could just reach her key. Lucy was shacking with anticipation. If this all went wrong, she'd have to be prepared to run for it. Unfortunately, her shaking was her downfall. Her hand shook so much that it bumped the keys on her ring. The jingle of her keys seemed to echo in her ears and then Zeref's eyes opened and he looked straight at her. Lucy was frozen with fear and she buckled to her knees, unable to withstand the pressure of his magic presence.  
"Give me the Eternal Key."  
Zeref took a step towards her, causing her to refocus again. In an instant, Lucy was on her feet and she began to run towards Magnolia Station, not daring to look behind her.

****

Hey guys! Thanks for reading this far; it really means a lot to me. Don't forget to tell me what you think if my story. Also, I've written up to chapter six, I just need to type them out on the computer. So stayed tune! :)


	5. Chapter 5

Natsu had already finished unpacking so he had enough time to write a quick note to Lucy when Happy came soaring through the bedroom window that always seemed to be open.  
"Hey Happy!"  
"There's no time to explain…"  
Happy had a hard time speaking as he tried to catch his breath.  
"Zeref's here and he's chasing Lucy!"  
Natsu's eyes flashed with panic for a split second but were quickly replaced with a look of violence.  
"Where is she?"  
"Lucy said to meet at Magnolia Station. She'll hold him off until then."  
Happy and Natsu both knew that she didn't stand a chance against Zeref. Without any notice, Natsu jumped out of the window that Lucy had kicked him through so many times. They've had so many laughs together and they've shed tears together. He chose Lucy to be his partner for a reason. That same Lucy was now facing death alone.  
_"It's always more fun when we're together."  
_Natsu ran even faster as he remembered her face that day on Tenroujima. Lucy had chosen her own pain so that he didn't have to suffer alone and she smiled at him; believing in him. She could have chosen to leave him behind and save herself but she wanted to stick with him until the end. Now it was his turn to stay with Lucy. Besides, he had promised her that he'd keep her safe.

The sky began to fill with gray clouds that would soon bring a thunder storm. Lucy wasn't paying attention that that right now though as she focused on keeping Zeref at least ten steps behind her.  
_I'm safe as long as he can't reach me_ she thought to herself. _He won't kill me right away since he needs this 'Eternal Key' that he thinks she has. But once he finds out that I don't have it, I'm dead for sure.  
_Lucy was about two blocks away from the station when it began to pour down rain. The town streets became slippery in a matter of seconds. Magnolia hasn't had a storm this bad in decades. Her blonde hair became slightly darker as she became wet from head to her toes.  
"Why does it have to rain now?!'  
Frustrated, she yelled at the clouds. They replied back very quickly with a deafening roar of thunder that shook her straight to the bones.  
_Note to self: Don't yell at the sky again._  
A sudden burst of pain in her left ankle caused Lucy to slip and fall to the concrete.  
"What happened? Why does my…"  
Zeref interrupted her.  
"Forgive me but I need you alive, for now."  
No… This can't be happening! She was so close! The station was just ahead of her. She could see it with her own eyes. She had to get there and meet Natsu.  
The last thing she was Zeref's hand reaching towards her, then everything went black. Thunder filled her ears as she felt something tug from inside of her chest.  
_What's happening to me? Natsu..._


	6. Chapter 6

Natsu felt a strange ache in his heart as he ran to save Lucy. Did something happen to her? A clap of thunder echoed across Magnolia but Natsu heard something else above the thunder that would haunt him forever. Lucy was screaming out in agony not too far from where he was.  
"Lucy!"  
He ran towards the sound of her voice and when he arrived at the scene, he realized he was too late. Zeref stood over Lucy's body, holding a golden key in his hands. He had a smirk on his face as he studied the key he had just gained.  
"Ah, Natsu, you've finally arrived. I'm afraid a little too late though as you can see."  
He gestured towards Lucy's lifeless body.  
"She was hoping you would save her, kind of pathetic, and the look on her face..."  
A shadow grew over Natsu's face as he stared at the body of the Celestial Spirit mage. This was all wrong; it had to be a dream. Natsu was planning on cheering her up once she got to the apartment that night and maybe take her to the harbor where they first met. He was planning on confessing how he felt towards her. None of this was supposed to happen. Lucy's supposed to be smiling right now and encouraging him to do his best. Instead, she was lying on the cold hard ground, motionless. Tears began to stream down his face and he was shaking all over.  
"Bring Lucy back you bastard!"  
Unexpectedly, Zeref began to laugh.  
"You really are a fool. Can't you see that she's still here with us? Look a little closer."  
Natsu's eyes caught the glint of the golden key.  
"No way... That can't be Lucy."  
Could it be possible that Lucy had turned into the key that Zeref possessed?  
"It's quite the opposite really. Lucy wasn't turned into the key; Lucy is the key, or rather this is the form of her soul. She is the Eternal Key!"  
None of this was making any sense to Natsu. So does this mean that Lucy's still alive within that key?

**Hey Guys! Thanks for reading this far and I hope you're enjoying the story. Just a heads up that I'm thinking of having up to 10 chapters but I'll see how it goes. Keep checking for new chapters.**


	7. Chapter 7

Everything felt strange to Lucy. The last thing she could remember was leaving her father's mansion after she finally couldn't handle living with him anymore. Now she has some weird pink mark on her hand and her head hurts. For some reason, Lucy felt like she was forgetting something important. The more she tried to remember, the worse the pain got in her mind. Oh well, if she can't remember it, it must not be that important. She looked around and saw... nothing? How could that be? It was almost as if the entire world had been painted over in black.  
"Hello?!"  
Her voice seemed to carry on forever. She finally came to the conclusion that she was all by herself when she saw a figure in the distance appear with a flash of light. Lucy looked a little closer and realized that she knew the person.  
"Mom, is that you?"  
The woman resembled her in so many ways from her blonde hair to the kindness in her brown eyes. There was no doubt about it; she was Lucy's mother.  
"Lucy, you've grown into a beautiful young lady just like I knew you would."  
Lucy felt her throat tighten as she tried to hold back the tears she felt coming on.  
"There are so many things I want to tell you but time is precious. Right now you're in the space between life and death and you need to make a choice that could end you life or the lives of your friends."  
_My friends? Who is she talking about?  
_Lucy knew that there was a reason she was there but she couldn't understand how it happened and who were these friends her mom is talking about? Lucy cried out in frustration.  
"Who are you talking about?! I have no friends or family members left that care about me!"  
Layla gave a small smile and stepped towards her daughter. She reached out and touched Lucy's face.  
"You may have forgotten them but they haven't forgotten about you. Remember who you really are. You aren't just a member of the Heartfilia family; you are a part of Fairy Tail's family. They're still with you, even now. _He's_ still with you and he's fighting for you as I speak."  
Lucy saw an odd image in her mind. A pink haired boy was just barely standing as he was covered in bruises and fatal wounds. His opponent was a boy with hair the colour of death himself. The pink haired boy took a step forward and said something that touched Lucy's heart.  
" You can fight me, curse me, even insult me but when you attack one of my friends, you better be prepared to go through me to finish the job! I was too late to save Lisanna years ago and I fought to get her back. Now don't think for a second that you can take away someone precious to me. I will keep fighting until all the bones in my body are crushed and I can't even move my fingers. I can still smell her scent lingering to that key so she's probably listening to me talk right now so I have a message for her: I'm coming for you Lucy! I made a promise to you right?!"  
And with that, the nameless boy ran forward, flame in hand, and then the image disappeared, leaving Lucy feeling lonelier than before.  
"Was that...Natsu?"  
As soon as she said his name, memories came flooding back into her mind. Phantom Lord, Galuna Island, the Tower of Heaven, Oracion Seis, Edolas, Grimoire Heart, Tenroujima; she remembered it all. She remembered Fairy Tail; her family and home. Natsu. He was, no, _is _her everything. He rescued her from her old life and gave her a hope and a future in Fairy Tail. Natsu had saved her countless of times and even now, he was fighting to save her. Then she thought of something else.  
"Dad; is he okay?"  
"Yes, he's happy to know that you're enjoying your life with those who love you."  
She and her mom embraced in a tearful reunion but Layla knew that time was short.  
"Listen to me my daughter; you are more than just a Celestial Spirit mage. Every person's soul has a different form but yours is a very rare type of soul. You soul has taken on the form of the Eternal Key."  
"Isn't that what Zeref's after?"  
"Yes. He wants the Eternal Key because it opens the doors to Heaven and Hell. Your soul is the key to the afterlife. If Zeref were to get hold of your soul, he would use it to control an army of demons."  
"But Zeref already has my soul."  
Layla shook her head.  
"He has merely removed your soul from your body. This has left you with three options to choose from, all of them leading to pain for someone."  
So basically she had to choose to cause someone hurt no matter what she chooses. Great.  
"What are my options?"  
"The first is that you could choose to let Zeref use your soul for his own purposes, and then you would go back to your body and live in whatever world he has created. You'll have no way of knowing if any of your friends survived or not."  
So she could still live but her friends would die and she'd be killing thousands of innocent people. Definitely not an option.  
"The second option is more painful for you. You can choose to end your life so that the Eternal Key no longer exists but you would be leaving your friends with the guilt of not being able to save you in time."  
A long time ago, Erza told her about the vision she had about Fairy Tail after she sacrificed herself to save everyone and that her choice had caused them all more pain than she had wanted. There was no way Lucy could put her friends through that much pain.  
"What's the third choice?"  
Her mom hesitated, clearly not wanting to say it out loud.  
"The final option is that you never existed. None of your friends would have memories of you and your life with them. However, you would come with me to the afterlife where you would be able to watch your friends grow up and live on."  
Could she really do that? Could she really just choose to be forgotten?  
Of course she could. She's Lucy Heartfilia, a Celestial Spirit mage and a member of Fairy Tail. If choosing to be forgotten would save her friends from harm, she would be willing to do anything.  
"I choose the third option. I choose to be forgotten and live here forever."  
Even though she was unaware of it, tears were slowly running down her face.

**Just letting you know that the story's not over yet so keep checking for new updates :)**


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